Pump



Feb. 11, 1969 A. F. ANERSON PUMP Sheet Filed April 4, 1966 Feb. l1, 1969A. F. ANDERSON 3,426,686

PUMP Fi1edApri14,19ee V sheet 2 @f5 Feb. 11,1969I A. F. ANDERSON3,426,686

PUMP Y' Filed April 4, 1966 sheet 3 of 5 Aff@ Feb. l1, 1969 A, F.ANDERSON PUMP Filed April 4, 1966 Y Feb. 11, 1969 A.*F. ANDERSON3,425,586

PUMP Filed April 4, 196e sheet 5 of s United States Patent O 9 ClaimsABSTRACT F THE DISCLOSURE A variable displacement piston pump of theswash plate or tilt box type is hereby provided that is characterized byan improved, simplied and economical structural assembly, notably anin-line insertion of piston pump subassemblies and components into oneopen end of an enclosing housing without necessity for individualmounting of the sub-assemblies or components in or to the housing, andcompletion of the assembly by simple attachment of an end cap. Aparticular feature resides in the improvement wherein the housing andend cap are separated on a line co-planar with the pivot axis of theswash plate Or tilt vbox and are provided with mating pairs ofsemicircular recesses which together form two bearings or journals, andwherein the swash plate or tilt box has integral trunnions journalled inthese bearings. This facilitates simple insertion of the swash plateinto the housing and subsequent securement of the same by simpleattachment of the cap without necessity for a separate mounting.

The assembly is further characterized by insertion into `the end of thehousing opposite said cap and onto a single drive shaft of a pair ofcompact rotary pumps, namely, a supercharger pump for pressure chargingthe inlet side of the piston pump and `a control -pump for controllingthe direction and amount of fluid pumped by the piston pump.

A further feature resides in the provision of a manually adjustableoverload control which automatically governs operation of the pistonpump pursuant to the manual adjustment, said control sensing the outputpressure of the piston pump and regulating as a function of saidpressure the pressure of the fluid discharged by said control pump,thereby automatically to regulate the displacement and the output of thepiston pump.

Variable displacement piston pumps of the character here include arotary cylinder barrel which abuts a stationary valve face located atone end of the barrel. The barrel is provided with a plurality ofcylinder bores which are arranged in a circle about the barrel axis andpistons are mounted for reciprocation in said cylinders. A drive flangerotated conjointly with but having universal movement relative to thebarrel is connected by ball and socket joints to the ends of connectingrods which are connected by other ball and socket joints at theiropposite ends to the pistons. A tilt box supports the drive flange andis adapted to be tilted by varying degrees relative to the barrelwhereby to vary the angle between the drive flange and the barrel andthereby vary the stroke of the pistons and the volume of fluid deliveredby the pump via inlet and outlet ports in said valve face.

The object of the present invention is provision of an improved pump ofthe character described, and particularly, the provision of a pumphaving a high capacity to size ratio, that is convenient and economicalto construct, and reliable over a long service life.

ICC

The objects and advantages of the invention will become apparent in thefollowing detailed description.

Now, in order to acquaint those skilled in the art with the manner ofmaking and using my improved pump, I shall describe, in connection withthe accompanying drawings, the `best mode presently contemplated -by mefor carrying out the invention.

In the drawings:

FIGURE 1 is a schematic diagram of the pump of the present invention andcontrol means therefor;

FIGURE 2 is a vertical longitudinal section of the pump, the view betingtaken substantially on line 2 2 of FIGURE 3;

FIGURE 3 is a cross-sectional view of the pump taken substantially online 3 3 of FIGURE 2;

FIGURE 4 is a horizontal longitudinal section taken substantially online 4 4 of FIGURE 3;

FIGURE 5 is a vertical longitudinal section taken substantially on line5 5 of FIGURE 3 showing means for variably tilting the tilt box and thuscontrolling the stroke of the pistons;

FIGURE 6 is a cross-sectional View taken substantially on line 6 6 ofFIGURE 2 showing the piston drive flange Aand a constant velocityuniversal joint between said flange and the cylinder barrel drive shaft;

FIGURE 7 is a front elevation of the main pump cylinder block as thesame would -be viewed from line 7 7 of FIGURE 2, but with the pistonsremoved;

FIGURE 8 is a view taken substantially on line 8 8 of FIGURE 2, showingthe porting of the main pump portion of my pump;

FIGURE 9 is a view taken substantially on line 9 9 of FIGURE 2 showing asupercharger portion of the Pump;

FIGURE 10 is a View taken substantially on line 10 10 of FIGURE 2showing a control pump portion of the pump;

FIGURE 11 is a horizontal longitudinal section taken on lines 11 11 ofFIGURES 2 and 3; and

FIGURE 12 is a fragmentary sectional view taken on line 12 12 of FIGURE2.

Referring first to FIGURE 1, I have depicted, schematically anddiagrammatically, the preferred embodiment of my pump and control meanstherefor. The pump is indicated generally at 10 and the controller orregulator at 12; the main or hydraulic power system of the pump isdepicted by pipes and/ or passages, and the control circuit or system isindicated by relatively ne lines. The fluid supply for the entire systemis maintained by a reservoir or the like (not shown) communicating withthe remainder of the system by supply and drain lines 100 and 101respectively.

The reservoir primarily supplies uid to a main pump 102 which is drivenby any suitable prime mover. In the preferred embodiment, a superchargerpump 105 and a i control pump 106 are embodied in the structure 10 andare driven by the same prime mover as pump 102.

The control pump 106 draws fluid from the reservoir supply line viapassage 107 and pumps the Same at a relatively low control pressure (eg.400 p.s.i.) via conduit 108 to a pressure regulator 109. The regulator109 is manually adjustable, as by means of a handle or knob 110, therebyto cause increase or decrease in the control pressure and by virtuethereof to increase the main pump output, as -will presently bedescribed. The uid at the regulated control pressure ilows to a four-wayreversing valve 112 including a reciproca-ble spool 113 having a centralneutral position, a forward position Vand a reverse position. In theneutral position, the valve ports are interconnected by the valve bodyand spool whereby the entire control system is at the same pressure 4andthus neutralized. In the forward position, the spool serves to connectline 108 to a forward control line 115 and a reverse control line 116with a vent or drain line 117 returning t0 the reservoir. In its reverseposition, the spool 113 reverses the connections effected in the forwardposition, i.e., connecting the line 108 to the reverse control line 116and connecting the forward control line 115 to the drain line 117.

The valve 112 may be operated manually, and is operable independently ofthe pressure regulator 109. Assuming the valve 112 is in forwardposition, control fluid at a regulated or adjusted pressure is fed vialine 108 to the forward control line 115. At the same time, the line 116is vented to the reservoir. Fluid in line 115 is fed to a hydraulicactuator 11561 for a four-way valve 120 and to a main pump directioncontrolling an output adjusting stroke cylinder 115b. The cylinder 115boperates to cause the main pump 102 to operate in one direction, i.e.,to pump fluid in one direction, and also operates upon increase anddecrease in the control pressure to increase and decrease the output ofthe pump 102.

The valve 120 includes a spool 122 centered in a neutral position bycentering springs 121, and the same in said position includes portsinterconnecting and serving to put the system all at the same pressurethereby to neutralize the system. Upon actuation by the actuator 115a,the valve is shifted to a forward position which will be described indetail hereinafter. Due to simultaneous actuation of the stroke cylinder115b, the pump will in this position of the valve be operating to supplyfluid under pressure via power line or conduit 145a to one or morereversible hydrostatic motors or a like load (not shown) to operate thesame. At the same time, hydraulic fluid is returned from the motors orthe like via conduit 145b which at this time is connected to the pumpinlet, whereby fluid is circulated in essentially a closed loop from thepump 102 via line 145a to the load and then back to the pump via line145b.

The conduit 14561 is also coupled to a conduit 146a which leads back tothe valve 120 and which at this time is coupled via the valve to aconduit 124 which leads to the pressure regulator 109, whereby fullsystem pressure is brought to bear on the regulator to the extent thatif system pressure exceeds a predetermined maximum the regulator will beopened or by-passed or vented, in known manners, to relieve or decreasecontrol pressure, whereby the stroke cylinder 115b will be automaticallyadjusted to decrease the output of the main pump 102 and thereby affordan automatic safety against excessive system pressures.

The conduit 145b is similarly coupled to a conduit 146b which leads tothe valve 120 and which at this time (forward position) is coupled bythe valve to the outlet 123 of the supercharger 105 to afford aninitially pressurized supply of fluid to the main pump 102. The outputpressure of the supercharger is maintained at a suitable level (e.g., 50psi.) via a by-pass 118 and a relief valve 119 coupled to a drain.

When it is desired to reverse the direction of the power fluid, it isonly necessary to operate the reversing valve 112 to its reverseposition, whereupon control fluid is supplied via reverse line 116 to ahydraulic actuator 116a for the valve 120 and a second pump directionand stroke adjusting cylinder 116b. At the same time, the actuator 11511and cylinder 115b are vented to the reservoir via line 11'7, whereuponthe actuator 116er may shift the valve 120 to reverse position and thecylinder 116b may take over control of the main pump. Fluid underpressure is then supplied from pump 102 via conduit 145b` to the load,the fluid being returned to the pump via conduit 145a. At the same time,the valve 120 has been shifted so that system pressure is transmitted tothe regulator 109 via conduit 14617, the valve 120 and the conduit 124;and the conduit 14613 is connected to the supercharger 105.

The main pump 102 is thus operable under the control of the pumps 105and 106, the valve 120 and the controller or regulator 12, whereby tosupply fluid under regulated pressure, in varying amounts and inopposite directions to any suitable load, such as one or morehydrostatic motors.

Referring now to FIGURES 2 to 12, the preferred physical structure ofthe pump 10 is illustrated as enclosed within a three-part housing ofbolted assembly including a main pump housing 14 having an end cap 15,and an auxiliary pump housing 16. The housing 14 has a cylindrical bore17 in one end thereof receiving a rotary cylinder barrel 18 which isprovided therein with nine axially extending cylinder bores 19 arrangedequidistantly in a circle concentric with an axial bore through thebarrel. Confined between the bottom of the bore 17 and the inner end ofthe barrel 18 is an annular valve plate 21 which is retained stationaryrelative to the housing by a pin 22 secured to the housing and extendinginto a slot or recess in the valve plate.

Extending axially through the barrel and plate is a drive shaft 23,aligned portions of the shaft and the barrel being complementarilysplined, as indicated at 24, whereby the two are interconnected forjoint rotation. The shaft extends inwardly beyond the valve plate 21into an axial bore in the housing 14, where it is journalled on bearings25 and united with a shaft extension 26. The extension 26 projectsthrough the main housing 14 and into the auxiliary housing 16 to drivethe auxiliary pumps 105 and 106 as will presently appear. At its end,the extension is journalled on bearings 27 supported in a bore in thehousing 16. A compression spring 28 is confined between opposedabutments on the shaft 23 and the barrell 18 whereby to bias the barrelinto engagement with the valve plate.

Outwardly of the barrel 18, and preferably inthe plane of the juncturebetween the housing 14 and the end cap 15, the shaft 23 is provided witha toothed portion 30 comprising part of a constant velocity universaljoint which is illustrated in FIGURES 2 and 6. As shown, the portion 30of shaft 23 is provided with nine equally spaced axially extending slots31, the same number as there are cylinders in the barrel 18. Each slotis comprised of a semi-cylindrical Outer portion, a radially innerportion of any desired configuration, and a radially inwardly extendingrecess or socket substantially centrally of said inner portion.

Encircling the toothed or slotted portion 30 of the shaft is a driveflange 32, the radially inner surface of which is provided with axiallyextending semi-cylindrical slots 33 of the same number as andrespectively aligned -with the slots 31. Mounted within each alignedpair of slots 31-33 is a constant velocity power transmission assemblycomprised in this case of a stem or stern pilot 34 and a ball element35. Each stem 34 comprises a radially extending rod having a sphericalinner end fitting within the socket part of the respective slot 31 andforming therewith a ball and socket joint. At its outer end, each sternis provided with an elongated parti-cylindrical head comforma'bly andslidably received in the respective slot 33. Each ball element 35comprises a hollow spherical segment journalled on the rod portion ofthe respective stern immediately below the head thereof, the sphericalsurfaces of the ball element together with the cylindrical surface ofthe head defining, in effect, a ball substantially completely fillingthe cross sectional area of the respective pair of slots 31-33 (seeFIGURE 6i). In use, as will presently appear, the stems 34 guide theball elements 35 in such manner that as the flange 32 is tilted relativeto the shaft the balls are guided to and retained in substantially thehomokinetic plane, i.e., the

plane bisecting the angle between the axis of the shaft and the plane ofthe flange, whereby to provide a constant velocity universal jointtherebetween.

For purposes of controlling the tilting movement of the drive flange,the same is journalled in or on a tilt box 36 comprising an annularbearing portion receiving the joint 30-35 and a pair of radiallyoppositely extending trunnions 37. Preferably, anti-friction bearings 38are provided between the drive flange and the tilt box to assure freerotation of the flange. The trunnions 37 are journalled by bearings 39in respective cylindrical bores formed by complemental semi-cylindricalrecesses 40 in the mating faces of the main housing 14 and the end cap15. By virtue of this construction, i.e., the housing 14 and the end cap16 and location of the universal joint in the plane of the juncturetherebetween, the tilt box is very conveniently mounted in the housingand the assembly 0f the trunnions and the two bearing parts is readilyand easily effected. Moreover, this construction accommodatesfabrication of the trunnion supports or bearings entirely interiorly ofthe housing assembly and interiorly of the end cap gasket 41, wherebyall problems of hydraulic leakage and the need for complex sealarrangements at the trunnions are eliminated.

At the outer side thereof, one of the trunnions 37 includes an eccentricextension 42 extending into a recess in the end cap and aligning itselftherein with the outer ends of a pair of pistons 115c` and 116Creciproca'oly mounted respectively in the stroke adjusting cylinders115b and 116b previously referred to. These cylinders are formed in theouter end face of the main housing 14 in spaced parallel relation to oneanother, in perpendicular relation to the plane of the housing end faceand to opposite sides of the tilt axis (the axis of the trunnions) ofthe tilt box 36. Consequently, the pistons 115C and 116C are operable,upon admission of fluid under pressure to the respective ones of ports115 and 116 (FIGURES 1 and 5) to tilt the box 36 and thus the flange 32in opposite directions about a neutral position wherein the box 36 andflange 32 are perpendicular to the shaft 23.

Each of the pistons 115C and 116C preferably comprises a cup-shapedpiston having an axially protruding Spherical head 43 universallymounting thereon a bearing shoe 44 disposed for engagement with thetrunnion extension 42. Interiorly of each piston, there is provided acompression spring assembly which is operable to normally bias therespective piston outwardly, but only to a limited extent. Each suchassembly preferably comprises an inner abutment 45 engaging the bottomwall of the respectively cylinder, a screw 46 adjustably threaded intothe abutment, a collar 47 slidably mounted on the screw for the limitedmovement accommodated by the screw head, and a compression spring 48confined between the abutment and the collar for normally biasing thecollar and the piston outwardly.

A further advantage of the described assembly of the housing 14, end cap15 and trunnions 37 is the ease and facility with which the pistons 115eand 116C may be mounted in and adjusted relative to the housing 14.Thus, this assembly is seen to be an important feature of the inventionleading to particular facility and economy of construction and to pumpcompactness.

Outwardly of the tilt box assembly, the end cap 15 includes an endclosure portion having a tubular central section mounting bearings 50and seals 51 for the outer end portion of the drive shaft 23, the shaftextending through the cap and having a splined end 52 for connectionwith any selected prime mover. When driven by such prime mover, theshaft rotates the constant velocity joint 3ft-35 and the barrel 18conjointly with one another, and also conjointly drives the pumps 105and 106.

The constant velocity joint and the barrel 18 conjointly rotate withthemselves nine piston and piston rod assemblies comprising theprincipal fluid impelling means of the pump. As shown in FIGURE 2, eachsuch assembly comprises a cup-shaped piston 55 reciprocable in arespective barrel cylinder 19 and a connecting rod 56 having a sphericalhead at each end thereof respectively engaging in a spherical socket inthe interior of the piston and an axially aligned spherical socket 57 inthe opposed face of the drive flange 32. As shown in FIG- URE 6, thesockets 57 alternate with and are preferably located on a longer radiusthan ball slots 33. Each connecting rod is secured to its piston by aC-ring or the like fitted within the piston and all of the connectingrods are retained in association with the drive flange by a retainerring '58 secured, as by bolts 59, to the face of the drive flange.

The shaft, drive flange, barrel and pistons thus rotate as a unit in thehousing. When the tilt box 36 is perpendicular to the shaft, and thusparallel to the barrel, the pistons simply rotate and do not reciprocateand no pumping pressure is applied to the fluid. However, when the box36 is tilted relative to the shaft, the drive flange assumes a positionwherein the distance between it and the barrel varies around the circleof rotation whereby the pistons and connecting rods are made toreciprocate relative to the cylinders l19. The stroke of the pistonswill depend upon the degree of tilt of the box 36, which is controlledby the pistons e` and 116C (whereby the latter derive the name strokepistons). Also, the stroke pistons control the direction of fluid flowsince when the upper one (FIGURE 5) is energized (forced outward), thepump pistons 55 will move into their cylinders as they rotate toward thebottom of the housing (FIGURE 2) and will move outward as they rotatetoward the top of the housing; whereas when the lower one of the strokepistons is energized the pump pistons will have the opposite movement.

In accordance with the pump piston movements, the housing 14 is providedat the inner wall of the bore 17 thereof with two substantiallysemi-circular ports 144a and 144b extending in opposite directions fromadjacent the top to adjacent the bottom of the housing, as is shown inFGURE 8. The valve plate 21 has complemental ports and serves as a wearplate between the barrel and the housing. For cooperation with theports, the inner or pump ends of the cylinders 19 are formed witharcuate ports 19a (FIGURE 7) complementing the ports 14441 and 144b.Communicating with the latter are passages extending inwardly fromopposite sides of the housing and constituting the previously describedconduits 14541 and 145b, respectively.

Also communicating with ports 144a and 144b are holes or passagesdrilled in the body or housing 14 and constituting the previouslydescribed conduits 14651 and 146b, respectively. These extend upwardlyin spaced parallel relation to one another and at their upper endscommunicate with a cross bore in the housing, which corresponds to andis numbered the same as the body of the previously described four-wayvalve (see FIGURE 3). The bore 120 includes a central enlarged areaintermediate the ports 146a and 146b, and the supply duct 123 from thesupercharger 105 communicates with this area. The spool 122 of the valveincludes enlarged lands at its ends and at its center, the latter one ofwhich is sufficiently small to fit within the enlarged central area ofthe bore 120 normally to maintain the ports 146a and 146b in opencommunication. The conduit means 124` for accommodating supply ofhydraulic fluid at system pressure to the controller 12 comprises a pairof spaced parallel drill holes 124a and 124b extending longitudinallythrough the housing 14 from respective locations in the bore 120(FIGURES 3 and rl1) and a horizontal cross bore 124 connecting the twodrill holes and opening to one side of the housing 14.

The valve bore 120 is closed at its opposite ends by threaded plugs 60which serve as abutments for the spool centering springs 121. Eachspring is preferably guided at its opposite ends within a bore in therespective plug and a retainer 125 slidably engaged with the respectiveend of the spool 122. The movement of each retainer is preferablylimited by engagement with a shoulder in the bore whereby each springserves only to retain the spool in or return it to its centered positionand is not itself capable of forcing the spool to an overcenterposition. Each retainer is perforate, whereby the respective end of thespool is maintained in open communication with the chamber formedbetween a respective end plug retainer. These chambers respectivelycomprise the actuators 115a and 116a previously described and are placedin communication with the respective control lines 115 and 116 byappropriate drill passages in the housing bearing the latter numbers(FIGURES 3, and 1l).

The control lines 115 and 116 are defined by spaced parallel holesdrilled both vertically and transversely of the body at the auxiliarypump side of the four-way valve 120, and by longitudinal holes openinginto the chambers 115:1 and 116:2 from the auxiliary pump end of thehousing 14. To facilitate economic formation of the pump, the latterholes are simply drilled through both of the transverse holes andselective control over iiuid flow is gained by simple plug inserts 6l.and 62 (FIGURE 11). Inserts 61 is relatively short and servesessentially to plug the outer end of the respective hole and to reclosethe wall between the two transverse holes. Insert 62 is of a lengthequal substantially to that of the respective longitudinal hole andincludes spaced lands sealing the wall between the longitudinal holesand sealing within the entry to chamber 115a. Ports are provided withinthe insert 62 to establish communication between the hole 115 and thechamber 1-15a, and the sealing portions of the two inserts serve to denea sealed path of communication between hole 116 and chamber 116a` Whencontrol fluid is fed from the regulator 12 to the line 115, uid pressureis applied to the stroke piston 115C and to the chamber 1-15a. Fluid inthe latter chamber causes the spool 122 to shift to the left as shown inFIGURES 3 and lvl, whereupon ports 124b is closed by the right end ofthe spool and communication is established between ports 146a and 124aand between ports 123 and 146b. Similarly, when pressure fluid is fed toline 116, the spool is shifted to the right to block off the ports 124aand to establish communication between ports 123 and 146a and ports 146band -124b. When fluid pressure is relieved, the springs 121automatically center the spool 122 in the bore 120.

As previously explained, the ports -124 are provided for conductingiiuid at main pump pressure to the regulator, and the port 123 isprovided to accommodate a pressurized source of fluid at the main pumpinlet. To insure that the latter is not supplied at an excessivepressure, the safety valve 119 previously described is ernbodieddirectly in the pump. Specifically, as shown in FIGURES 2 and l2, theport 123 communicates via the enlarged central area of the bore 120 witha port leading to a cross bore 11-8 in the body 14. The outer end of thebore 118 is counterbored for reception of a valve seat 1-19a and aspring pressed valve member K119 held in place by a threaded plug 63inserted in the counterbore. Communicating with the space between theseat 119a and the plug 63 is a-n inclined bore -118a leading into themain pump bore 17, whereby the pressure fluid at the pump inlet may beautomatically vented into the latter boreA when the pressure isexcessive.

The components of the piston pump 102 will inherently have a smalldegree of fluid leakage, and it is intended that the fluid resultingfrom leakage and inlet fluid relief be accumulated in the bore 17 toprovide lubrication for the physical parts of the piston pump. Excessfluid is drained from the housing to the reservoir via a radial drainport 101 in the housing 14.

To the extent thus far described, the apparatus comprises in essence themain pump 102, and in particular a high pressure variable displacementpiston pump of special economy and compactness and long service life.The valves 119 and 120 are not necessary to operation of the pump perse, as the pump operates essentially via the main or power ports 145aand 145b under the variable volume and flow reversing control of thestroke pistons 115e and 116e. However, the valves 119 and 120 areembodied compactly and expeditiously within the housing 14 andfacilitate (a) pressurized supply of uid to the inlet side of the pump,whether the inlet be the p-ort 145a or the port 14512, and (b)transmission of outlet pressure to the control system whether the outletbe port 145a or port 145b.

While the pressurized fluid inlet supply and the uid for the controlsystem could be furnished from other sources independent of the pump 10,it is a particular feature of this invention to incorporate thesupercharger 105 and the control pump 106 directly in the housing 14 ofthe main pump, whereby to provide an especially compact and economicalcomplete pump and control systern.

As previously noted, the main pump shaft 23 is equipped with anextension 26 which is utilized to drive the pumps 105 and 106 conjointlywith the pump 102. Specifically, the extension 26 is keyed directly tothe rotors of the two pumps, which are both preferably gerotor pumps.

Referring to FIGURES 2, 3, 4 and 9, the supercharger pump 105 is housedwithin a counterbore 65 at the rearward end of the housing 14, thehousing being provided at the end wall of the counterbore with an inletport 66 communicating with a radial port constituting the previouslydescribed inlet from the uid reservoir, and an outlet port 67communicating with the port or passage 123. Preferably, a wearplate 68having complementary inlet and outlet ports is abutted against thissurface of the housing.

Mounted within the counterbore 65 is a first gerotor pump comprising anouter eccentric locator ring 71 retained against rotation relative tothe housing, a rotary and eccentrically shiftable gerotor ring 72, and arotary gerotor hub 73 keyed to the shaft extension 26 for rotationtherewith. The gerotor hub 73 is smaller than the ring 72 and the twohave complemental radially extending protuberances thereon meshed at thepoint of closest approach of the eccentric ring 70 to the shaftextension 26, whereby the hub rotates and slides the ring 72 therebycausing the same to perform a pumping function. Thus, uid is deliveredfrom the inlet 100 to the port 123 at a predetermined pressure.

Next outwardly from the pump is the wearplate 74 having a port 75therein complemental to and aligned with the port 67, whereby the port75 serves as a second outlet from the pump 105 and an inlet for thecontrol pump 106. The pump 106 is constructed essentially the same asthe pump 105, but with such dimensioning as to develop the appropriatecontrol pressure. Specifically, the control pump comprises (FIGURE 10)an eccentric locator ring 76 retained against movement in a bore in theauxiliary housing 16, a gerotor ring 77 rotatable and shiftable withinthe ring 76 and a gerotor hub 78 keyed to the shaft extension 26. Anannular control pump outlet 79 is formed in the housing 16 and the samecommunicates with a radial port constituting part of the previouslydescribed control uid supply 108. As shown in FIGURE 4, the stationarycomponents of the two auxiliary pump assemblies are commonly secured tothe housing 14 and 16 by a single longitudinally extending pin 80.

Thus, it is seen that the invention provides an extremely compact andeconomical apparatus embodying in a single structure a high pressurevariable volume piston pump, a supercharger, a control pump, controlmeans lfol' the piston pump, and automatically operating valve means forcorrelating the functions of the several pumps.

While I have shown and described what I regard to be the preferredembodiment of my invention, it is to be appreciated that variouschanges, rearrangements and modifications may be made therein withoutdeparting from the scope of the invention, as defined by the appendedclaims.

I claim:

1. In a variable displacement piston pump having trunnion supported tiltbox means operatively guiding a plurality of pistons reciprocable in thecylinders of a rotatable cylinder barrel and tiltable relative to the-barrel to cause variable stroking of the pistons in the cylinders, theimprovement comprising a pump housing having an end face substantiallycoplanar with the pivot axis of the tilt box trunnions, and end caphaving an end face complemental to and abutted against the first-namedend face, complemental pairs of substantially semicircular recesses insaid end faces conjointly comprising journals for the tilt boxtrunnions, said recesses being located inwardly of the margins of saidend faces and said end faces including abutting planar marginal portionssubstantially coplanar with the pivot axis of said trunnions andy,completely circumscribing said tilt box and its trunnions, and a ilatgasket between said marginal portions sealing the pump housing andsealingly enclosing said trunnions in said housing, said pump housingand end cap and one of the tilt box trunnions having extensions -withinthe confines of said marginal portions generally paralleling thetrunnion axis, the trunnion extension having a flat face substantiallycoplanar with the trunnion axis and facing toward the pump housing7cylinder means formed in the extension of the pump housing and openingat said end face of said housing, stroke piston means in said cylindermeans projecting from said end face and engaging said flat face of saidtrunnion extension transversely and eccentrically of the axis thereof,and means for supplying fluid under pressure to said cylinder means tocause said piston means to rotate said trunnion extension and therebytilt the tilt box.

2. In a pump as set forth in claim 1, a pair of said cylinder means andpiston means disposed transversely and to opposite sides of the axis ofsaid face of said trunnion extension, and m'eans for selectivelysupplying fluid under pressure to said cylinder means to cause saidpiston means to reversely rotate said extension and thereby tilt thetilt box in opposite directions from a central porition perpendicular tothe cylinder barrel.

3. In a variable displacement pump, a housing, a piston pump comprisinga cylinder 4barrel rotatable in the housing, pistons reciprocable in thecylinders in the barrel, ports in said housing communicating lwith thecylinders in the barrel `as it rotates to conduct fluid to and from saidcylinders, a tilt box operatively guiding said pistons and variablytiltable to control fluid ilow through said ports, fluid pressureoperated piston means for variable tilting said tilt box, auxiliary pumpmeans in said housing coupled to and rotated conjointly with said barrelfor supplying pump controlling fluid under pressure to said fluidpressure operated piston means, and overload control means connected toand operable by the fluid pressure in the outlet of the piston pump andhaving connection with the outlet of said auxiliary pump means forrelieving the pressure on the pump controlling fluid thereby to controlthe piston pump as a function of its outlet pressure, said fluidpressure operated piston means comprising a pair of fluid operatedstroke pistons in said housing operatively connected to said tilt box,said stroke pistons normally positioning the tilt box in a neutralposition and being selectively operable to tilt the same in oppositedirections to varying degrees to control the amount and the direction offluid llow through said ports, said overload control means comprisingmanually operable valve means for supplying control iluid from saidauxiliary pump means selectively to said stroke pistons at selectivelyvariable pressures.

4. In a pump as set forth in claim 3, a four-way valve reciprocablymounted in said housing and communicating at its ends respectively withsaid stroke pistons for reciprocation in accord with the selectiveoperation of said stroke pistons, port means in said housing leadingfrom each of the ports of said piston pump to said four-way valve, saidmanually operable valve means including pressure regulator means, andconduits leading from said fourway Valve and said auxiliary pump meansto said regulator means, said four-way valve including port meansestablishing communication between the port of said piston pump thenserving as the outlet port thereof and said regualtor means, saidregulator means correlating the piston pump output and the pressure ofthe control fluid.

5. In a pump as set `forth in claim 4, said auxiliary pump means alsoincluding a supercharger pump and port means in said housing leadingfrom its outlet to said four-way valve, said four-way valve includingport means establishing communication between the lastnam'ed port meansand the port means leading from the port of said piston pump thenserving as the inlet port thereof.

6. A variable displacement pump, comprising, in combination, a mainhousing having a bore therein and a hole extending coaxially inwardlyfrom the bottom of said bore, a piston pump including a barrel rotatablein said bore and having a circular array of cylinders therein parallelto its axis, said barrel and said housing having engaging end faces atthe bottom of said bore normal to said cylinders, said housing having insaid face a pair of separated but substantially semi-circular portscomplementary to and aligned with the circle of said cylinders andcommunicating with the cylinders, pistons and said cylindersreciprocable toward and away from said ports, tilt box means at theopposite end of said bore operatively guiding said pistons and variablytiltable relative to said barrel about an axis generally parallel to aline joining the mid-points of said ports to vary the stroke of saidpistons, said tilt box means including trunnions extending outwardlyfrom opposite sides thereof along said axis, said housing having an endface substantially coplanar with said axis and having semicircularrecesses therein complemental to and receiving said trunnions, an endcap for said housing having an end face complemental to and abuttingsaid end face of said housing and having semi-circular recesses thereincomplemental to the recesses in said housing and complemental to andreceiving said trunnions whereby said trunnions are journalled betweensaid housing and said end cap, said recesses being located inwardly ofthe margins of said end faces and said end faces including abuttingplanar marginal portions substantially coplanar with the pivot axis ofsaid trunnions and completely circumscribing said trunnions, a flatgasket :between said marginal portions sealing the pump housing and endcap and sealingly enclosing said trunnions in said housing, a driveshaft extending through said end cap and said tilt box and coupled tosaid barrel, said shaft extending axially through said Ibarrel and intosaid hole, and bearing means in said hole and in said end cap rotatablysupporting said shaft.

7. In a pump as set forth in claim 6, said housing at its opposite endhaving a second bore therein communicating with said hole, auxiliarypump means in said second bore, and an end cap closing said second boreand enclosing said auxiliary pump means, said shaft extending throughsaid hole land into said second bore and being coupled to said auxiliarypump means for driving the same.

8. In a pump as set forth in claim 7, said auxiliary pump meanscomprising a pair of gerotor pumps closely coupled to one another andsaid barrel.

9. In a pump as set forth in claim 7, a valve bore in said housingintermediate said barrel and said auxiliary pump means, ports in saidhousing leading from each of the first-named ports and from saidauxiliary pump 11 12 means to said valve bore, and a valve in said valvebore 3,075,472 1/ 1963 Garnier 10S-162 selectively movable to establishcommunication between 3,160,109 12/ 1964 Kline 103--162 said auxiliarypump and each of said rst-named ports. 3,212,263 10/ 1965 Hann 60-53 C.3,257,959 6/ 1966 Budzich 103-162 References ed 5 FOREIGN PATENTS UNITEDSTATES PATENTS 628,472 4/1936 Germany.

3,251,304 5/1966 Knight 103--37 2,356,101 8/ 1944 Temple 103--5 WILLIAML. FREEH, Primary Examiner.

2,718,758 9/1955 Minshall et al. 103-165 X 2,769,393 11/1956 Cardin@ etal. 103-5 10 U.s. C1. X.R.

3,016,834 1/1962 Deska et al. 103-5 X 103-5, 162

